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PubMedDate not supplied

Leishmania mexicana amazonensis: heterogeneity in 5'-nucleotidase and peroxidase activities of mononuclear phagocytes during in vivo and in vitro infection.

The degree of maturation of cells of the Mononuclear Phagocyte System (MPS), during in vivo and in vitro infection by Leishmania mexicana amazonensis, was evaluated in this study. The macrophages' differentiation was assayed by cytochemical characterization at the ultrastructural level, using two well-established markers: 5'-nucleotidase enzyme activity, for revealing the mature cells; and the peroxidase activity present in the cell granules to demonstrate immature mononuclear phagocytes. Only a few macrophages, demonstrating 5'-nucleotidase positive reaction in both the plasma membrane and within their cytoplasmic vesicles, were found scattered in the chronic inflammation at the L. m. amazonensis lesions in albino mice. However, by the peroxidase activity analysis, we were also able to demonstrate the presence of immature MPS cells, which predominate, together with parasitized vacuolated macrophages, in chronic lesions induced in this system by L. m. amazonensis. The implications of these results on the pathogenesis of murine cutaneous leishmaniasis are discussed.

5'-Nucleotidase↗
PubMed1985

5'-Nucleotidase inhibitory activity of nucleoticidin, melanocidin A and melanocidin B. Structure-activity relationships.

Nucleoticidin and melanocidins A and B exhibited potent inhibitory activity against 5'-nucleotidases from rat liver membrane and snake venom. These inhibitors are polysaccharides with highly branched side chains having at least disaccharide units. This conclusion was supported by the results with polysaccharides of known chemical structures. The inhibitors showed non-competitive inhibition with respect to AMP, and urea-treatment caused a marked decrease or a disappearance of the 5'-nucleotidase inhibitory activity. Therefore, it is concluded that steric factors also play an important role in their inhibitory activity.

5'-Nucleotidase↗
PubMed1985

New 5'-nucleotidase inhibitors, melanocidin A and melanocidin B. I. Taxonomy, fermentation, isolation and biological properties.

New 5'-nucleotidase inhibitors named melanocidins A and B were produced by Nocardioides sp. 1681 J. They were isolated from fermentation broth by trichloracetic acid extraction, ethanol precipitation and CM-cellulose and DEAE-cellulose column chromatography. They inhibited 5'-nucleotidase activity from snake venom but not from rat liver membrane at 200 micrograms/ml. They also show antitumor activity against melanoma B16.

5'-Nucleotidase↗
PubMed1986

Effect of 5'-nucleotidase inhibitors on mouse immune system and experimental murine tumors.

Nucleoticidin and melanocidins A and B exhibited potent inhibitory activity against 5'-nucleotidases from rat liver membrane and snake venom. Nucleoticidin retarded growth of Sarcoma 180 solid tumor, and melanocidins A and B prolonged the survival period of mice bearing B16 melanoma. These inhibitors enhanced phagocytic activity, interleukin-1 production and superoxide-generating activity of murine peritoneal macrophages. The tumor necrosis factor was also induced by the inhibitors. These results suggested that 5'-nucleotidase inhibitors inhibit tumor growth by modification of the immune system.

5'-Nucleotidase↗
PubMed1988

[Diagnostic value of 5'nucleotidase in primary and secondary neoplasms of the liver].

64 patients with various malignant neoplasms (6 primary and 18 secondary liver cancers, 40 tumors without evidence of hepatic involvement) entered a comparative study measuring serum levels of 5'nucleotidase, AFP, TPA, CEA, CA 19-9. In primary liver cancer, 5'nucleotidase true positive rate was 100% (vs 67% of AFP, TPA, CA 19-9 and 33% of CEA); in secondary liver tumors it was 67% (vs 11% of AFP, 44% of CEA, 55% of CA 19-9 100% of TPA). Diagnostic sensitivity was 75% and specificity 90.5%.

5'-Nucleotidase↗
PubMed1989

Functional characterization of ecto-5'-nucleotidase-positive and -negative human T lymphocytes.

Functional studies were performed on human peripheral blood T lymphocytes stained with goat anti-5'-nucleotidase antibodies and separated into ecto-5'-nucleotidase (ecto-5'-NT)-positive and -negative populations using the FACSTAR fluorescence-activated cell sorter. On the average, ecto-5'-NT+ T cells contained 34 +/- 13% CD4+ and 55 +/- 15% CD8+ cells, whereas ecto-5'-NT-T cells contained 65 +/- 12% CD4+ and 23 +/- 8% CD8+ cells. Staining with anti-5'-NT antibodies did not significantly alter the ability of unseparated T cells to proliferate in response to PHA or PMA, or in a MLR. However, prior incubation with anti-5'-NT antibodies did inhibit the ability of irradiated T cells to provide help for PWM-stimulated Ig synthesis by as much as 55%. In five separate experiments, ecto-5'-NT-T cells demonstrated an equal or better ability to incorporate [3H]TdR after PHA stimulation or in a MLR, as compared with ecto-5'-NT+ T cells. Similarly, ecto-5'-NT- T cells were not diminished in their ability to provide help for autologous B cells in a PWM-driven system. Clearly, the inability of ecto-5'-NT- T cells from patients with a variety of immunodeficiency diseases to function in these assays cannot be explained solely by their lack of ecto-5'-NT activity. In contrast, ecto-5'-NT-positive and -negative T cells showed markedly different dose-response curves for proliferation in response to PMA. Ecto-5'-NT+ T cells responded to lower doses of PMA (1.0 ng/ml) than did ecto-5'-NT- T cells and showed a two- to eight-fold greater rate of [3H]TdR incorporation at 3 to 10 ng of PMA per ml. Ecto-5'-NT+ T cells may have a protein kinase C that is more accessible or more easily activated or may utilize an alternate pathway of activation when stimulated with low concentrations of PMA.

5'-Nucleotidase↗
PubMedDate not supplied

[Effect of various immunostimulants on 5-nucleotidase activity of macrophages of peritoneal exudate in the mouse].

All the immunostimulators studied, independently on their biological origin and chemical structure, decreased the 5-nucleotidase activity in macrophages of mice peritoneal exudate, thus indicating activation of these cells. The most distinct inhibition of the enzymatic activity in macrophages was induced by preparations of microbial origin. The decrease of the 5-nucleotidase activity in macrophages was observed in mice of CBA strain only after intraperitoneal administration of the preparations, while in non-linear animals--after subcutaneous or itraperitoneal injections.

5'-Nucleotidase↗
PubMed1988

Determination of the characteristics, properties and homogeneity of rat brain microsomes. Binding of lactate dehydrogenase, malate dehydrogenase and 5' nucleotidase to microsomal membranes.

Quantitatively, the amount of microsomes obtained using dimethyl sulfoxide is larger than that obtained from sucrose solutions (Centelles, Franco & Bozal (1986) Biol. Chem. Hoppe Seyler 367, 461-475). In this paper it is demonstrated that from a qualitative point of view they appeared to be indistinguishable with respect to molecular characteristics. Thus, both types of microsomes had the same behaviour in experiments of isopicnic ultracentrifugation with Percoll, isoelectric focusing and gel permeation. In these experiments, the 5'-nucleotidase, lactate dehydrogenase and malate dehydrogenase activities bound to the microsomal fraction were also studied. Lactate and malate dehydrogenase activities were always found in free and membrane-bound form. In contrast, 5'-nucleotidase activity was always encountered bound to microsomal membranes.

5'-Nucleotidase↗
PubMed1985

[Effect of benzodiazepines on 5'-nucleotidase activity in rat brain].

Experiments on 330 rats were made to study the influence of benzodiazepines (diazepam, dormicum and phenazepam) on 5'-nucleotidase activity in brain homogenates. It was discovered that diazepam and dormicum in doses of 3 and 4 mg, phenazepam in doses of 3.75 and 5 mg per 200 g bw provoked a 16-20% reduction in 5'-nucleotidase activity. The maximal effect of diazepam (3 and 4 mg doses) was attained 1 h after intraperitoneal injection, that of dormicum (3 mg) 30 min and of phenazepam (5 mg) 1 h after intraperitoneal injection. It is assumed that benzodiazepines are involved in AMP metabolism.

5'-Nucleotidase↗
PubMed1986

Tiazofurin metabolism in human lymphoblastoid cells: evidence for phosphorylation by adenosine kinase and 5'-nucleotidase.

The exact route of metabolism of tiazofurin, a novel nucleoside with antitumor activity, is controversial. Using human cell lines severely deficient in salvage nucleotide enzymes, we were able to identify the route of activation in tiazofurin metabolism. With loss of adenosine kinase activity by mutation in two lymphoblastoid cell lines, CCRF-CEM and WI-L2, the growth sensitivity to tiazofurin decreased by 6- and 3-fold, respectively. In contrast, the mutant lines were about 3000- to 1500- and 16- to 4-fold more resistant to the structurally similar tiazofurin analogues pyrazofurin and ribavirin, respectively. Other mutants with defective deoxycytidine or uridine kinase activity showed normal sensitivity to all three analogues. Both cell lines with defective adenosine kinase activity accumulated about 50% wild-type levels of tiazofurin-5'-monophosphate and thiazole-4-carboxamide adenine dinucleotide analogue of tiazofurin at cytotoxic concentrations of the drug. Extracts of wild-type lymphoblasts catalyzed the phosphorylation of tiazofurin in the presence of adenosine 5'-triphosphate and Mg2+. Loss of adenosine kinase activity in the mutant extract eliminated this phosphorylating activity for tiazofurin consistent with the notion that adenosine kinase catalyzes phosphorylation of tiazofurin. However, an enzyme activity that catalyzed the phosphorylation of tiazofurin in the presence of inosine-5'-monophosphate as donor and Mg2+ was detected in the extracts of both wild-type cells and adenosine kinase-deficient mutants. The monophosphate donor specificity, divalent metal, high salt requirement, and nucleoside acceptor specificity of this enzyme activity paralleled that of a 5'-nucleotidase (EC 3.1.3.5) which catalyzes inosine phosphorylation. In addition, tiazofurin phosphorylation was competitively inhibited by inosine and the apparent Ki value was similar to the apparent Km value for inosine phosphorylation. These results indicate that two enzymes, adenosine kinase and a cytoplasmic 5'-nucleotidase, are functionally important anabolizing enzymes for tiazofurin in human cells.

5'-Nucleotidase↗
PubMed1986

Human placental cytoplasmic 5'-nucleotidase. Kinetic properties and inhibition.

The kinetic properties of highly purified human placental cytoplasmic 5'-nucleotidase were investigated. Initial velocity studies gave Michaelis constants for AMP, IMP, and CMP of 18, 30, and 2.2 microM, respectively. The enzyme shows the following relative Vmax values: CMP greater than UMP greater than dUMP greater than GMP greater than AMP greater than dCMP greater than IMP. The activity was magnesium-dependent, and this cation binds sequentially with a Km of 14 microM for AMP and an apparent Km of 6 mM for magnesium. A large variety of purine, pyrimidine, and pyridine compounds exert an inhibitory effect on enzyme activity. IMP, GMP, and NADH produce almost 100% inhibition at 1.0 mM. Nucleoside di- and triphosphates are potent inhibitors. ATP and ADP are competitive inhibitors with respect to AMP and IMP as substrates with Ki values of 100 and 15 microM, respectively. Inorganic phosphate is a noncompetitive inhibitor with Ki values of 19 and 43 mM. Nucleosides and other compounds studied produce only a modest decrease of enzyme activity at 1 mM. Our findings suggest that the enzyme is regulated under physiological conditions by the concentrations of magnesium, nucleoside 5'-monophosphates, and nucleoside di- and triphosphates. The nucleotide pool concentration regulates the enzyme possibly by a mechanism of heterogeneous metabolic pool inhibition. These properties of human placental cytoplasmic 5'-nucleotidase may be related to the control of nucleotide degradation in vivo.

5'-Nucleotidase↗
PubMed1985

Activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid and alkaline phosphatase and nucleotide pyrophosphatase in human thyroid.

The activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid phosphatase, alkaline phosphatase and nucleotide pyrophosphatase was assayed in human thyroid glands. The 5'-nucleotidase activity was higher than that of AMP deaminase which suggested that AMP undergoes degradation primarily as a result of dephosphorylation in thyroid tissue. A high acid phosphatase activity was noted as compared to that of alkaline phosphatase activity. In toxic goitre the increase in adenosine deaminase and acid phosphatase was observed together with the decrease in pyrophosphatase activity.

5'-Nucleotidase↗
PubMed1985

5'-nucleotidase activity in the spinning gland cells of Diacrisis obliqua (Arctiidae: Lepidoptera).

5'-nucleotidase activity in the spinning gland cells of an Indian moth, Diacrisia obliqua has been studied for the first time during prefunctional, functional and postfunctional phases of development. The enzyme seems to play an active role in the metabolism of silk secretion. Differential utilization of 5'-nucleotidase substrate in the growing and degenerating cells has been studied and discussed.

5'-Nucleotidase↗
PubMed1984

The heterogeneity of 5'-nucleotidase activity in lymphoblasts of acute lymphoblastic leukemia, demonstrated by an improved cytochemical method.

5'-Nucleotidase activity was demonstrated in the cell membrane of normal and leukemic lymphocytic cells by an improved cytochemical method. In the normal blood lymphocytes an average percentage of 20.6 +/- 2.9 5-nucleotidase positive (5 N +) cells were found. Among the various cases investigated, in 12 "null"-acute lymphoblastic leukemias an increased percentage of 5 N + blast cells was observed (33.4 +/- 27.95%). The heterogeneity however of the individual percentage of 5 N + blasts of each case in this group, was remarkable (0-89%) and not readily explicable. We also found a considerable percentage of 5 N + circulating lymphoma cells in patients with leukemic nodular poorly differentiated lymphocytic lymphoma (18.5 +/- 9.9%). In contrast, a low percentage of 5 N + leukemic cells was observed in the B and T chronic lymphocytic leukemia, B and T prolymphocytic leukemia, hairy cell leukemia and T acute lymphoblastic leukemia.

5'-Nucleotidase↗
PubMed1984

[5'-nucleotidase activity in the organs of cattle, sheep and swine].

Studied was the activity of 5'-nucleotidase (EC3.1.3.5.) in organs (liver, lung, spleen, heart, kidney, small intestine, skeletal muscles of the loin region, bones, and ruminal wall, resp., stomach wall in swines) of three groups of cattle, sheep, and pigs with 12 animals in each. With cattle the activity of the enzyme was essentially high in the liver (9.92 +/- 1.19) and substantially lower in the lungs (5.81 +/- 0.38), small intestine (3.84 +/- 0.61), and kidneys (1.09 +/- 0.08). In the remaining organs the enzyme activity was either negligible or in traces, and in the ruminal wall there was no such activity at all. In sheep the enzyme activity was highest in the lungs (0.61 +/- 0.5), followed by the liver (6.92 +/- 0.44), and the spleen (4.35 +/- 0.39). The activity was almost one and the same in the heart, kidneys, and small intestine (2.43-3.42), and there were only traces in skeletal muscles and bones. With pigs the activity of 5'-nucleotidase was highest in the small intestine (6.30 +/- 1.14); it was lower in the liver, spleen, and stomach (5.94-4.42), and lowest--in the heart, body muscles, and bones (0.9-0.33). To determine the diagnostic value of the blood serum level of the enzyme it is necessary to carry out investigations with these species of animals when affected with various diseases.

5'-Nucleotidase↗
PubMed1980

[Distribution of 5'-nucleotidase activity in the subcellular fractions of rabbit brain cortex].

The specific activity of 5'-nucleotidase was measured in the fractions of myelin, synaptic membranes, heavy and light synaptosomes and purified mitochondria of brain cortex of intact rabbits. The enzyme specific activity in these fractions was practically the same and made up to 2.2, 2.1, 1.98 and 1.8 mkmoles of Pn per mg of protein per hr. The differences between the specific activities of the four fractions were statistically insignificant. The 5'-nucleotidase activity of the heavy synaptosome fraction was 2 times as low as that of the other fractions as was equal to 0.92 mkmoles of Pn per mg of protein per hr. This value is statistically different from those obtained during the analysis of the other fractions.

5'-Nucleotidase↗
PubMed1980

Ecto-5'-nucleotidase activity in lymphoblastoid cell lines derived from heterozygotes for congenital X-linked agammaglobulinemia.

Lymphoblastoid cell lines were established from female relatives of patients with congenital X-linked-agammaglobulinemia by Epstein-Barr virus transformation of their peripheral B lymphocytes. Cell lines derived from presumed carriers were characterized by low ecto-5'-nucleotidase activity and a reduced percentage of surface immunoglobulin-bearing cells. Measurement of ecto-5'-nucleotidase activity in newly established lymphoblastoid cell lines may provide a means for the identification of heterozygotes for congenital X-linked agammaglobulinemia.

5'-Nucleotidase↗
PubMed1982

[Changes in Na+, K+-adenosinetriphosphatase and 5'-nucleotidase activities in cell membrane isolated from rat liver after acute white phosphorus poisoning].

Na+, K+-ATPase and 5'-Nucleotidase activities in rat liver plasmamembranes after "in vivo" intoxication with a single dose of white phosphorus (10 mg/kg b.w. "per os") are investigated. Na+, K+-ATPase activity is significantly increased 1 hour and inhibited 12 hours after intoxication. 5'-Nucleotidase is strongly increased at 1, 2 and 4 hours after poisoning and is significantly decreased at 12 hours. The enhancement of both the enzymatic activities is evident prior to triglyceride accumulation in rat liver. Our results suggest that lipid fluidity of cell membrane is early and mildly affected during white phosphorus poisoning.

5'-Nucleotidase↗